Niger troops started an anti-militant operation that included an incursion into Mali after they were attacked by an "armed terrorist group", according to the country's defence ministry.
Niger's defence ministry has said its troops killed 79 "terrorists" in operations last week that involved a foray into neighbouring Mali.
Troops from the army's anti-terrorist Almahaou operation began the search after they were attacked by an "armed terrorist group" in Niger's western town of Tiloa on March 10, the ministry said on Friday.
It also came after at least 17 Nigerien soldiers were killed last month in Intagamey, another town in the vast western region of Tillaberi, one of several areas currently under a state of emergency due to militant attacks.
The pursuit, carried out by air and land forces, led to the Hamakat area of Mali, the hideout of the alleged perpetrator of the February 10 attack, the ministry said.
A security source contacted by AFP said the operation's extension into Mali was "unprecedented".
The ministry did not report any military casualties during the operation.
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The attacks the army reported took place in Tillaberi, which straddles Burkina Faso and Mali - two countries hit by a militant insurgency.
The region has faced repeated attacks since 2017 by armed groups linked to Al Qaeda and the Daesh network.
Thousands of soldiers and civilians have been killed and two million people have been displaced by the Sahel-wide conflict, of which Mali remains the epicentre.
In early March, Niger's armed forces Chief of Staff General Salifou Mody was received in Bamako by Mali's junta leader Colonel Assimi Goita.
Niger said they discussed co-operating on security along the two countries' more than 800-kilometre border.
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